This cure is applicable to Linux based systems such as Kubuntu and Ubuntu.
Stop those annoying pop-ups intruding into your workspace by simply running Spotify Music player in a second desktop window and leave it maximised as follows:
- Go to System Settings/Workspace Behaviour/Virtual desktops and increase the number of desktops to 2
- Activate second desktop by typing Ctrl-F2
- Launch Spotify and select the music you like to play
- Switch back to main desktop by typing Ctrl-F1 or select desktop from System Tray icon and continue working!