flare-up

leimahdus A sudden outbreak, outburst or eruption (originally of flame, but now used more generally of any violent activity)
(quote-book)
(quote-book)|year=2009|page=250|isbn=978-1-58950-750-1|passage=The disadvantage of the underfired grill is the potential for flareups, which can cause a burned spot or carbonization. Not only do these taste bad, but they are also carcinogenic.
A sudden intensification in activity