Question

Which two processes are at equilibrium in a saturated sugar solution?

Answer 1

A saturated sugar solution will show two processes at equilibrium. They are...
1. the dissolving of sugar molecules
2. the precipitation of sugar molecules

Sugar molecules are intact when dissolved. Their OH functional groups make them polar and easily dissolved in water.

Here's an analogy.

Think of sugar molecules as being analogous to plates. Sugar crystals are analogous to a stack of plates and dissolved sugar molecules are like plates which have been set on the table (not touching other plates).

A saturated solution is like a table which has some plates set out (dispersed dissolved particles) and other plates in a stack (sugar crystal). The balanced processes of dissolving is like taking plates off the stack to be set out. The crystallization process is like taking plates that were set out and putting them back onto the stack of plates.

Equilibrium means that plates will transition back and forth between being in the stack and being set out, but the number of plates set out and the number of plates in the stack will stay the same.

Check out this answer which discusses the same concept but for salt.
http://socratic.org/questions/why-is-a-saturated-salt-solution-at-equilibrium