Was with my mom once stuck in a traffic jam in the hot summer heat. Don't know why but Volvos seem to have a problem with overheating...
Anyway, a tube that pumps the air conditioning gas built up too much pressure (PV=nRT ) due to the heat and blew apart. Very loud bang, lots of "smoke" which was actually the escaping coolant gas.
My mom as usual completely overreacted and made a big deal of it. It was pretty obvious for someone remotely mechanically-conscious that it was the air conditioning hose, especially since the car became very hot after that.
After a while, I managed to calm her down and get a move on. I am still trying to decide whether exploding gas hose > mom or not.