break out is a verb meaning "start abruptly". It carries 5 recorded senses.
move away or escape suddenly
“The horses broke from the stable”
“Three inmates broke jail”
“Nobody can break out--this prison is high security”
take from stowage in preparation for use
become raw or open
“He broke out in hives”
“My skin breaks out when I eat strawberries”
“Such boils tend to recrudesce”
Definitions, synonyms and semantic relations for break out come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.