The 'laughter' group
These nouns indicate what someone starts to do. They are usually used with the verb break or burst.
into applause into laughter into sobs into song into song into tears into a grin into a smile
Her face broke into a smile.
There is a tremendous feeling of elation, the sort of feeling that makes even non-singers burst into song.
She fell to her knees in the bathroom she was cleaning and burst into tears.