How to fix volume jump to 100%?

You have probably wrong configuration of PulseAudio daemon.

1) open file "/etc/pulse/daemon.conf" as super-user (root)
2) remove all lines that contain "flat-volumes = yes" (without quotes)
3) add line "flat-volumes = no" (without quotes)
4) save file
5) restart your computer (or just restart pulseaudio daemon)

If you think the default configuration of your system is wrong, you
should report bug at a bug tracker of your distribution.

See https://bugs.launchpad.net/nuvola-player/+bug/980362/comments/26 for more details.