verb

burn or shine with a sudden intensity.

the bonfire crackled and flared up

blaze,flash,flare up,flame,burn unsteadily,burn violently,burn up,gleam,glow,glisten,sparkle,glitter,flicker,glimmer,scintillate,burn,be ablaze,be alight,be on fire,be in flames,be aflame,blaze up,go up,go up in flames,be afire,be ardent