foam vs form bubbles

foam is a noun but form bubbles is not a noun.

Word	Noun	Adjective	Verb	Adverb
foam	Yes	No	Yes	No
form bubbles	No	No	Yes	No

As verbs, foam and form bubbles are synonyms defined as:

Other synonyms of foam include effervesce, fizz, froth, sparkle.

foam (noun)	form bubbles (noun)
a mass of small bubbles formed in or on a liquid
a lightweight material in cellular form; made by introducing gas bubbles during manufacture

foam (verb)	form bubbles (verb)
become bubbly or frothy or foaming	become bubbly or frothy or foaming