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Synonyms for Bubble (same or very similar meaning)

WordNet sense 1 (a speculative scheme that depends on unstable factors that the planner cannot control):
house of cards

WordNet sense 2 (flow in an irregular current with a bubbling noise):
babble, burble, gurgle, ripple, guggle

WordNet sense 3 (expel gas from the stomach):
belch, burp, eruct

From the ODE community, based on WordNetadd/edit