ぼっとwith a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly

薪(たきぎ)にボッと火(ひ)がつきました。

The fire flared up suddenly in the firewood. {with a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly}

ボッとした顔(かお)の彼女(かのじょ)は頼(たよ)りないです。

She, with her absent-minded face, is unreliable. {with a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly}

ライターの火(ひ)がボッと音(おと)を立(た)ててつきました。

The lighter's flame flared up with a whoosh. {with a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly}

新聞紙(しんぶんし)がボッと燃(も)える様子(ようす)を彼(かれ)はボーッと見(み)ています。

He is vacantly watching the newspaper burn up in a blaze. {with a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly}

突然(とつぜん)台所(だいどころ)からボッと火(ひ)の手(て)が上(あ)がった時(とき)は、心臓(しんぞう)がバクバクしました。

When the flames suddenly flared up from the kitchen, my heart pounded with fear. {with a roar (of flames), with a whoosh, flaring up, suddenly blushing, in a daze, absent-mindedly, vacantly, abstractedly, blankly, idly, dimly, hazily, faintly, vaguely, indistinctly}