During the "Hymn" by Shikele, within one beat of the end of the piece, (at 4 minutes 31 seconds into the recording of that track), during a soft tympani ending, a bass string on John Lee's bass broke with a big thunk sound. It is rumored that this "thunk" fit perfectly with the music and is the reaon why the concert was so well received.
Click on the SoundRecorder picture
to hear 8 seconds that includes the sound of the bass string breaking. If you listen carefully (might require headphones) you can hear a soft tympani drum roll before the break and one very soft tympani beat afterwards. That last tympani beat is the last sound on that track. I'm not sure if it was also the last note and I'm not sure if anyone in the audience heard it after the load sound of the bass string breaking. I think many of the listeners who didn't actually see the string break, must have thought the string-breaking sound was part of the composition.
See here for a childrens story based on the above.