Leopold Stokowski gave the Philadelphia premiere of Ravel’s Bolero as an “encore” at a Friday afternoon concert.

The newspaper critics had all left the hall, and so once again word of mouth had to prove its effacy, for at the Saturday night concert, after the last number, the audience applauded with unusual fervour and would not let up. Time and time again Stokowski came out to bow and returned to the wings, while the applause grew deafening. They knew what they wanted, and so did Stokowski, but he remained dead-pan. Finally, he walked to the front of the stage, signaled for silence, and wit baby-faced innocence asked quietly, “Would you like to hear it?” All hell broke lose.

Chasins, Abram (1979) Leopold Stokowski. London: Robert Hale, p.102.