I've done it, but only once. And I was in a position where I knew I'd be able to find one without any real issue. My sister did the same and really struggled, narrowly avoiding having to move back in with our mom.

That having been said, since you're asking for advice, I'd recommend telling your boss about your frustrations, but not that you're planning on leaving. If he's worth his salt, he'll work to make improvements so either you will be happier or your replacement will be. Promising conversations are nice, but talk is cheap. Life is not. If one of those conversations leads to a new position, preferably in writing, you're golden. I'd just be leery in today's economy.

As someone that once spent 15 months unemployed between jobs I can tell you I am very adverse to the idea of ever leaving one job before having my next one queued up and ready to go.

I too, was very confident I could get another job fairly quickly. That feeling carried me through the first 3 months. By month 5, however, I was starting to realize my confidence may have been misplaced.

Only you can be the final arbiter of how realistic your prospects are, but based on my experience, a job or workplace environment would have to be truly atrocious (inflicting, or leaving me open to, serious physical, mental, emotional, or legal troubles) for me to leave it without a "plan b" already in place.

That said, I totally understand your desire to do right by your boss and inform him in person. That would be my inclination as well.

If he is a reasonable human being, and the situation is not something that can be adjusted to the point you would stay, maybe he can work with you on a flexible departure schedule. One that gives you the chance to secure a more concrete job offer, and allows him time to scout a replacement. Heck, you might even be able to help get the new guy up to speed before you tie everything up.

You need a plan, man. I too, want to quit my job. However, in order to do so, I need to sell my house, roll my equity into a crappy cash property in a new metro, and am prepared to deliver pizzas or some other part time work. If you have a plan, yes. If you don't, no go. Step one in quitting is to remove as many bills as you can beforehand, IMHO.

Do what’s best for YOU! Worrying about THEM finding a replacement is very generous BUT your boss may simply do things you don’t expect. I don’t know the type of business, but I’ve seen many bosses pay back with a “oh, don’t wait till next month, today will be you last day”.

You may think you are doing them a favor, and being a professional exemplary employee. But you are putting the company’s interest before yours and risking losing more paychecks than you planned to for them. If they loved you, they’d care about your health and reduce your traveling time, they don’t because that’s against their interest. It’s business. You should treat it like business also.

I’d only tell the boss when I am ready to give my 2 weeks notice over the phone.

I’d start looking for a new job in the meantime.

I'm intrigued because the level of risk-aversion displayed in the comments is much higher than I was expecting. My motivation for telling my boss now was to do the right thing by him and allowing him more lead time to arrange a replacement (as well as taking the opportunity to have a difficult conversation in person rather than by phone or email). There is no particular urgency in leaving from my side (other than the level of travel in my current role is poor for my health) I just think we are all better off if the transition is planned.

If I line up my new job first I would probably only be able to give my current employers the statutory four week notice period.

You are far too trusting, he will not hesitate in dropping you from the roster in a heartbeat. You should never give up a paying job without having your backup plan ready to go in it’s place. Your boss won’t want you in the company of other employees or customers as long as you are heading out the door.

No way I would quit without having other income.

Give him constructive criticism, explain the issues in a way that you don’t convey that you are quitting. This way, if things get better, you don’t have to quit. Also it might give you enough time to get your resume together and line up a new position before you quit.

Never ever quit a job without a new one lined up and a firm "start" date.
You don't need to tell the boss face to face, but you should schedule a phone exit interview with him when you give your two weeks notice.

Only if i had a minimum of 6 months of bill & living money. Otherwise, I would take the opportunity to speak with my boss "in a effort to resolve isdues & improve conditions", creating the illusion you want to stay. I wouldn't leave until I had a sure ace in the hole.

Do not quit or give your notice until you have the other job....

I would only quit if I had enough financial resources lined up to help me through the transition. That would be another job, enough money in the bank, or some other access to funds to tide me over. Otherwise, I'd save up and/or wait until I had that in place.

I've done it before, but I don't recommend it. Unless you've saved enough to keep you afloat for a few months, you're putting yourself in a position to be homeless or borrowing from family/friends which indebtment comes at a cost sometimes too.

It's more irresponsible to quit without a plan. Just flat out is.

However you are in charge of your own life. Best of luck.

Best time to get another job is while you still have one. Someone suggested having an honest rundown of you criticisms of the company with him but without pulling the trigger. That's a better plan.

I definitely would not quit before I had something lined up. You can always Skype or set up a GoToMeeting if you want a face to face

If your boss is flying to Australia to meet with you I am assuming your position is essential in that area. To leave them, without the respect of training a replacement, is not full adult.

Unless you have several months of savings or can go feral and live in the wild, hunting game and scratching up roots.

You need another job in hand.

I have done it, a couple of times. Once the job I thought I had wrapped up was cut. And once I took a buyout that included a year's pay, but still didn't find a good job until after the money ran out. Sometimes the satisfaction of quitting a job you hate is worth it. But it never seems to affect your employer as much as you think it will.

Would I? No. Should you? I can't answer that. I work freelance so I know all about the worries of figuring out how long you can pay for things/life until the money runs out. The hope is, obviously, that the next gig is right around the corner, but it might not be. If I were ever be in a position where I had a steady full-time, non-contract, permanent job and I were looking to move to something else, I'd rather have something lined up. But that's just me. Everybody is different.

I would not quite until you have something else lined up. A "promising conversation" is not an offer of employment. You are less important to your current employer than you think. Depending on what kind of industry you are in, you might not be able to give advance notice and instead be told to pack your desk immediately. Most companies will give you an an exit interview and you can lay out all your reasons for leaving there.

It’d be situational. Fuck it, just do it. You’ll have another lame job before long.

Well I'm self-employed but even when I work for other people I never worry about it I'm a Tradesman it basically means I have skills in all areas of construction so it's always been very easy for me to get work I never worry about it

From experience, I can tell you that you are taking a real risk. It could work out, or it could be a real disaster.

It could prove a bit risky in my opinion. You don’t say why you want to leave your current position, so it is hard to give advice without that information. Perhaps after your chat with the boss he will offer you better conditions or pay, if that is why you wish to leave, but you have to have that conversation with him. You are correct to say these things are better conducted face to face. As far as leaving without another position, my son did that a few years ago and it took him some time to get another suitable job. Promising conversations don’t always lead to positive outcomes unfortunately, so to quote the old proverb.....a bird in the hand etc.......!

you wrote that your boss is on the other side of the world, but you didn't mention what kind of relationship you have with him. My boss is a multiple hours flight away from me, but we talk & e-mail enough that the relationship is very solid. If I decided to leave this job, I'd let him know why & my time-line, in order to help him get someone else in place & train my replacement (which I've done at 2 previous jobs as well, leaving on very good terms with amazing references and confidence in my replacements )...
However, it all comes down to how much you trust the company (historically, do they immediately show someone the door if they say they're unhappy or plan on leaving?) and how much you trust your boss vs how much you need to be a good person for your own psyche's sake.
As everyone else has pointed out, there is a downside risk, here. If you can't afford to be without the income, you may need to hold on longer and have the conversation when you're actually at the point of leaving.

No way! If you get behind, it is so hard to get caught up again!! Unless you have the savings to hold you over, and even then, if it takes a while to land another job, would you have enough savings? I wouldn't leave until you have a start date for a new job. I speak from experience!