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):

effervescing
    adj 1: emitting or filled with bubbles as from carbonation or
           fermentation; "bubbling champagne"; "foamy (or frothy)
           beer" [syn: bubbling, bubbly, foaming, foamy,
           frothy, effervescing, spumy]