(intransitive, simultaneously euphemistic and, usually,hyperbolic) to be consumed by and destroyed in fire (which is only implied) such that smoke is the only evidence of something having happened (ash, smut, etc. notwithstanding)
As one may make substitutions for either of the phrase's two primary elements (the verbal partir and its complementary en fumée), a number of alternative phrasings, representing different levels of formality and used with varying levels of frequency, are possible: