During my bike tour in Bretagne, France, in 2008 I attended a Fest Noz and heard a traditional music style, the kan ha diskan (call and response singing, while people are dancing).
I had no idea what the songs were about, but I was hooked :)
Unfortunately I did not look up the the name of the artists I heard back then, but it might have been the adorable frères Morvan (hear them here).