bulge vs pop out

bulge is a noun but pop out is not a noun.

Word	Noun	Adjective	Verb	Adverb
bulge	Yes	No	Yes	No
pop out	No	No	Yes	No

As verbs, bulge and pop out are synonyms defined as:

Other synonyms of bulge include bug out, bulge out, come out, pop, protrude, start.

bulge (noun)	pop out (noun)
something that bulges out or is protuberant or projects from its surroundings

bulge (verb)	pop out (verb)
swell or protrude outwards	come out suddenly or forcefully
cause to bulge or swell outwards	exit briefly
bulge outward	bulge outward
bulge out; form a bulge outward, or be so full as to appear to bulge	appear suddenly or unexpectedly; happen unexpectedly