This is the 7863rd most frequent Japanese word.
噴き出す
"To spout, gush, or burst out."
噴き出す is used here to describe an eruption or spewing of lava by a volcano.
火山が噴き出して、周囲に溶岩を広げた。
The volcano erupted and spewed lava around.
噴き出す is used here to express the action of bursting into laughter suddenly.
彼は冗談を聞いて思わず噴き出してしまった。
He burst out laughing upon hearing the joke.
噴き出す indicates the physical gushing or spouting of water in this context.