definition of
flare up

[1] #1 flare up v. ignite quickly and suddenly, especially after having died down; "the fire flared up and died down once again". wn

[2] #2 flare up v. erupt or intensify suddenly; "Unrest erupted in the country"; "Tempers flared at the meeting"; "The crowd irrupted into a burst of patriotism". wn