If she is unscrewing the radiator cap why is her leg being pulled up above her head? Don't think that "she's going to blow" she's already squirting.
I always make it point to replace the regular radiator cap with one that has a pressure release lever. After the lever is pulled and the pressure is safely released, unscrewing the radiator cap is next. That's because I used to have a car that would over heat every 50 miles. Therefore I filled up jugs of water I kept in the trunk.
One time in a tiny Alabama town, I pulled into a church yard where the local children were milling around waiting for their parents to show up and take them home from vacation bible school. I pulled out my recycled jugs of liquor and refilled the radiator.
Their jaws dropped open. They may still be talking about me.
I learned that lesson years ago! Not a good idea at all! Steaming, smelly, dirty water drenching one teaches a lesson in a hurry!
Oh, & your radiator blowing is not fun either...