Chem demo explanation help!!?

there was a demo with two beakers. the first filled with water had a few drops of an unknown liquid added into it. the second had an unknown liquid as well. a paper resistant to liquids was place on top of the first beaker, and then that first beaker was placed upside down on top of the second. suddenly in the first beaker, the liquid turned very purple-pink. now, i have no idea what caused that as all the liquids added are unknown. somone help me out, thanks :)