Decrepitation is the breaking of a substance usually accompanied by the emission of a crackling sound. An example for a substance which decrepitates on heating is lead nitrate

Lead(II) nitrate

Lead nitrate is an inorganic compound with the chemical formula Pb2. It commonly occurs as a colourless crystal or white powder and, unlike most other lead salts, is soluble in water....

(Pb(NO₃)₂). The crackling noise which several salts make when suddenly heated, accompanied by a violent exfoliation of their particles. It has been attributed to the sudden conversion of the water they contain into steam. It is also shown by most ammonium salts and by barium nitrate. It is an important characteristic property that is used in dry tests within the laboratory.