It was 1997 and we were in Santiago de Cuba for Carnaval (it happens in mid-summer, not at mardi gras time) and we heard a rumor that Juan Formell and his crew were going to play a free gig, but nobody knew when. Turned out they had to wait until after Fidel's speech finished (it was being broadcast on every radio in the city). That eventually happened some time after midnight -- after a mere 4 and a half hours (short for the legendary long-winded el Jefe). The crowd was huge, and the cheap malty slightly sour beer dispensed from ancient tanker trucks soon ran out, but it was definitely a memorable night.
Te Pone La Cabeza Mala (standard translation: 'You make my head spin') was a massive hit on the island at the time, and each time they sang the chorus everyone made this spinning circular motion around their heads. These days I don't listen to timba too much, but at the time those indefatigable incessant rhythms were fresh, a new direction with Juan Formell in the vanguard. Needless to say, I went out and picked up the CD the next day, just for the title track alone.
There's a bit more on Los Van Van here.