thermal event 

An exothermic reaction where large amounts of smoke are generated but no flames are observed.

My house was subject to a thermal event and was reduced to ashes. I didn't see it, so it must not have been a fire.

thermal event by coldandbothered November 20, 2010

unexpected thermal event

Engineer doublespeak for "shit caught on fire"

Press 5 had an unexpected thermal event
Translation: shit went sideways and we had to call the fire department.

unexpected thermal event by Mark Barker June 24, 2021