This is the 12386th most frequent Korean word.
달아올랐다
"Heated up" or "became excited."
달아올랐다 is used to describe the physical phenomenon of a face becoming flushed due to excitement.
그의 얼굴이 흥분으로 달아올랐다.
His face flushed with excitement.
달아올랐다 indicates the overheating or warming of the body under the influence of external heat.
뜨거운 태양 아래 그는 온몸이 달아올랐다.
Under the hot sun, his whole body overheated.
달아올랐다 is metaphorically describing the atmosphere becoming more intense and heated as the debate grows lively.