bubble vs burble

bubble is a noun but burble is not a noun.

Word	Noun	Adjective	Verb	Adverb
bubble	Yes	No	Yes	No
burble	No	No	Yes	No

As verbs, bubble and burble are synonyms defined as:

Other synonyms of bubble include babble, guggle, gurgle, ripple.

bubble (noun)	burble (noun)
a dome-shaped covering made of transparent glass or plastic
an impracticable and illusory idea
a speculative scheme that depends on unstable factors that the planner cannot control
a hollow globule of gas (e.g., air or carbon dioxide)

bubble (verb)	burble (verb)
expel gas from the stomach	flow in an irregular current with a bubbling noise
form, produce, or emit bubbles
cause to form bubbles
rise in bubbles or as if in bubbles
flow in an irregular current with a bubbling noise