burst out vs crop up

burst out and crop up both are verbs.

Word	Noun	Adjective	Verb	Adverb
burst out	No	No	Yes	No
crop up	No	No	Yes	No

As verbs, burst out and crop up are synonyms defined as:

burst out and crop up: appear suddenly or unexpectedly; happen unexpectedly

Other synonyms of burst out include pop, pop out, pop up.

burst out (verb)	crop up (verb)
erupt or intensify suddenly	appear suddenly or unexpectedly; happen unexpectedly
give sudden release to an expression
appear suddenly or unexpectedly; happen unexpectedly