http://bps-research-digest.blogspot.com/2011/11/what-triggers-earworm-song-thats-stuck.html
I found this article on attempting to explain earworms (why certain songs get stuck in our heads). Research on this article explains it to be as a result of either:
Contact with certain people, specific rhythms you encounter, certain situations which relate to the songs meaning or lyrics, situational (where the song was heard), stress, tiredness or boredom.
Links to Ebbinghaus' memory research of 'involuntary memory retrieval', but no one explanation or cause can show why certain songs get stuck in our heads. It is more than likely, however, that cues are the main cause for the memory of a certain song to be involuntarily remembered.
