Question

to break out (e.g. of laughter)

Accepted Answer

if a noise breaks out, it begins suddenly (e.g. The smiles broaden, laughter breaks out)

Front	to break out (e.g. of laughter)
Back	if a noise breaks out, it begins suddenly (e.g. The smiles broaden, laughter breaks out)

E.G Breaks Laughter Noise Begins Suddenly Smiles Broaden