burst vs fall in

burst is a noun but fall in is not a noun.

Word	Noun	Adjective	Verb	Adverb
burst	Yes	No	Yes	No
fall in	No	No	Yes	No

burst (noun)	fall in (noun)
the act of exploding or bursting
rapid simultaneous discharge of firearms
a sudden flurry of activity (often for no obvious reason)
a sudden intense happening

burst (verb)	fall in (verb)
come open suddenly and violently, as if from internal pressure	break down, literally or metaphorically
break open or apart suddenly and forcefully	become part of; become a member of a group or organization
emerge suddenly	to take one's place in a military formation or line
burst outward, usually with noise
force out or release suddenly and often violently something pent up
move suddenly, energetically, or violently
cause to burst
be in a state of movement or action