But wait! Robin was right, my thermistor DID explode yesterday. How you ask? I have no idea.
What happened is that I printed stuff throughout the day and on the start of the god-knows-which print I extruded some filament to prime the nozzle. I wanted to remove the excess filament before the Z axis reached home with a pair of tweezers, so that it doesn't stick somewhere it isn't supposed to. I do that all the time.
But this time, as soon as I touched the brass nozzle part of my UBIS hotend with said tweezers, the thermistor exploded like a firecracker: flash, bang and all...
I had no clue that was even possible, and know even less about how/why it actually happened. For starters, I'm pretty sure the thermistor isn't supposed to be electrically connected to the brass nozzle in any way, and it must have been for this to happen. I'm guessing some static discharge ended it's life, I see no other reason why it would happen so suddenly.
The moral of this short story is: yes, thermistors can explode, so watch out how you insulate the leads!