Why does sugar turn black when concentrated Sulfuric acid is added to sugar?

Answer: Concentrated Sulfuric acid is a strong hygroscopic substance. Adding concentrated H2SO4 to sugar causes the H2SO4 to absorb all the water content of the sugar and the sugar is converted to carbon. So the sugar turns black.

C12H22O11 + Conc. H2SO4 = 12C + [11H2O + H2SO4]