The Collaborative International Dictionary of English v.0.48:

Decrepitate \De*crep"i*tate\, v. t. [imp. & p. p.
   Decrepitated; p. pr. & vb. n. Decrepitating.] [Cf. F.
   d['e]cr['e]piter.]
   To roast or calcine so as to cause a crackling noise; as, to
   decrepitate salt.
   [1913 Webster]