Open the Apple Music app
Start playing a song
Tap the MiniPlayer at the bottom
Tap the Up Next icon
Turn off AutoMix if it is enabled
On iPhone or iPad, go to Settings
Tap Music
Turn off Crossfade if it is enabled
On Mac, open the Music app
Choose Music
Click Settings
Open the Playback tab
Turn off Crossfade if it is enabled
Check that any DJ or party-style playback setting is disabled