Conversation so far:
when were the Pixies made?
In January 1986, Thompson formed the Pixies with Santiago.
What was their first album?
In 1987, the Pixies released an 18-track demo tape, commonly referred to as The Purple Tape.
What was their most popular song in the demo?
CANNOTANSWER.

Question: Was that demo album popular?
Self-contained rewrite: Was The Purple Tape demo album by The Pixies popular?