Stop in for a cup of coffee

I'm not an expert like you guys are... but I would think if the head gasket was blown it would overheat... especially if it was shoving that much coolant out?

FYI-- Being who I am... I would tap the radiator cap with a rock and see if it loosened something up if I was stuck along the road and didn't have a hammer or tire iron to try to tap it with... but then that's what I do in situations like that... sorryyyyyyy