"Boiling water without a heat source... Using compression/
expansion (pressure differential)... or, similar to the hot side of an air conditioning unit. No fire needed, just the ability to compress the liquid."

I'm assuming that this was just a rhetorical, toss-it-out-there idea. After all, which are you most likely to be able to do in a survival situation, dredge up debris to make this iffy contraption, or make a fire with almost anything else, by comparison?

Sue