Itallian composer Paganini is be seen as first solo virtuoso in modern sense.
During his lifetime his violin virtuosity was be seen as unbelievable.His 4 Violin concertos are quite hard to play.

Most important tunes :

Capricio Nr.1,
Capricio Nr.2,
Concerto for Violin Nr 1 Allegro and Adagio

O.F.D This list is still incomplete