It's not uncommon for bands to release an album, become known for it, and then the next album is their last.  This doesn't have to be a physical album; there are bands that had released many albums and not been known for them.  After they "make it" (i.e., one of the albums in their brood is recognized, wins awards, makes money, etc., etc.) then the pressure mounts to release an album as commercially successful as the "first" (again, keep in mind that it doesn't ACTUALLY have to be their first album.)

 

Internal strife, bad publicity, dwindling support: these are the things that can kill bands.

 

Some of you probably aren't old enough to remember the 'teen bands' of the 80's.  Tiffany; Debbie Gibson; NKOTB; Roxette (admittedly, we were fortunate that these bands/singers sunk into obscurity as quickly as they did) but it happens, and happens frequently.

 

That, in summary (quickly) is the 'sophomore jinx'