With albums/singles of a certain name length but only one song (the one I found was https://open.spotify .com/album/4KELHasdg1dkgY2TJBvwvA), the page becomes just large enough that it decides to add a scroll bar (without the bar that you move up and down inside of it). That makes the page smaller horizontally, and the album art+info is shrunk to compensate. This makes the page small enough that it doesn't think it needs a scroll bar, and it removes it. The album art+info is then expanded a little bit... beginning the process once again. It's not that much of a problem- it's rather funny, actually- but it is a graphical issue that should be fixed.
It seems this only happens when the page updates- when a song is playing, or when you mouse over something. It happens on Chrome (on Windows, haven't installed the desktop app yet after things happened) on a 15.6-inch screen (1366x768, in case it helps some GUI dev fix this).