I had a cheap chinese battery "blow up" in a flashlight late one night
Middle of the night I hear a pop- and "see" a green or maybe blue flash-
wake up-some acrid smoke in room-and a flashlight burning(rubber coated) near the bed

What happened-the bulb suddenly went bad-no light-while I was using it a few hours earlier
But I didn't turn-push the rear switch-OFF
the bulb burned out-but somehow it shorted for a few hours until enough heat built up-and POP- it blew the headlight off the tube
Nasty surprise- cheap chinese 123 batteries- 3.0 or 3.7 volts
Nice-expensive flashlight unfortunately
Yeah they will sorta explode-produce plenty of heat if no reaction energy is removed(no light)-it all just sits in the battery