The only time i can recall any clapping in a cinema was during BATMAN FOREVER.
The scene at the beginning where BATMAN escapes from the safe which has just been pulled out of the building by TWO FACE in a helicopter. BATMAN shoots a wire at the safe, cuts the cable connected to the helicopter, and the safe falls perfectly back through the blown hole and rests back into its original position.
The audience clapped like mad, probably because it was so unbelievable.
I just looked at my girlfriend at the time, and we both shrunk into our seats laughing.
Admittedly, i did the old ROCKY thing during ROCKY IV, same as all the other kiRAB in the audience when i watched it as youth but, ive never witnessed anybody clapping at the end of a film, though i have heard people did at the end of INCEPTION from a friend