Concerto for Orchestra (Bartók)
The fourth movement, called Intermezzo interrotto by Bartók, has a flowing melody with a time signature which keeps changing. There is also a theme which pokes fun at the march tune in Dmitri Shostakovich's "Leningrad" Symphony (No. 7). There is a very difficult bit for the timpani where the player has to play lots of different pitches in a very short section.