Guess I wasn't entirely clear -- venting liquid is 'boom city.'

A while ago some idiot 'entrepreneur' was reselling propane bottles that had been modified for agricultural use (marking foam for agricultural applications). The valve was attached to a tube that went to the *bottom* of the tank. If you connected that to a BBQ, you would get pure liquid propane, and if you hit the igniter you would singe more than your eyebrows.