The Collaborative International Dictionary of English v.0.48:

Effervesce \Ef`fer*vesce"\, v. i. [imp. & p. p. Effervesced;
   p. pr. & vb. n. Effervescing.] [L. effervescere; ex +
   fervescere to begin boiling, incho., fr. fervere to boil. See
   Fervent.]
   1. To be in a state of natural ebullition; to bubble and
      hiss, as fermenting liquors, or any fluid, when some part
      escapes in a gaseous form.
      [1913 Webster]

   2. To exhibit, in lively natural expression, feelings that
      can not be repressed or concealed; as, to effervesce with
      joy or merriment. Effervescence

WordNet (r) 3.0 (2006):

effervesce
    v 1: become bubbly or frothy or foaming; "The boiling soup was
         frothing"; "The river was foaming"; "Sparkling water" [syn:
         foam, froth, fizz, effervesce, sparkle, form
         bubbles]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "effervesce":
   assibilate, be enthusiastic, blubber, boil, boil over, bubble,
   bubble over, bubble up, burble, buzz, carry on over, enthuse,
   ferment, fizz, fizzle, go on over, guggle, gurgle, gush, gush over,
   hiss, hush, lisp, make much of, plop, rave, rave about, rhapsodize,
   seethe, shush, sibilate, simmer, siss, sizz, sizzle, sneeze, sniff,
   sniffle, snore, snort, snuff, snuffle, sparkle, spit, splutter,
   sputter, squash, squelch, squish, swish, take on over, wheeze,
   whish, whistle, whiz, whoosh, work, zip