Wiktionary
burst into tears
vb. (context idiomatic English) to suddenly start weeping
Usage examples of "burst into tears".
Astasia burst into tears and ran from the room, slamming the door.
Her lower lip began to quiver, and then Pasha burst into tears, turned, and ran.
At least give me your word that when your time comes 'round you won't ask me if I like the lace or the silk best, then burst into tears when I pick the wrong one.