When conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ is poured on the cane sugar, acid acts as dehydrating agent which removes moisture from sugar and sugar turns into spongy mass of carbon called sugar charcoal.
When conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$ is added to ${\mathrm{CuSO}}_4$ . $5{\mathrm{H}}_2\mathrm{O}$ , acid acts as dehydrating agent, which removes crystalline water. The salt converted into anhydrous salt which has white.