The temperature of boiling is very important, as it directly effects the final sugar concentration and moisture content of the sweet. For a fixed concentration of sugar, a mixture will boil at the same temperature at the same altitude above sea-level, and therefore each type of sweet has a different heating temperature.
A solution is a mixture of a solvent and a solute. A solvent is a liquid in most cases, and the solute is the powder or dissolving material. So a solution is mixing liquid (say, water) with the powder (salt or sugar).
The diagram can be described in terms of three zones: (a) Unsaturated/Not saturated Zone (b) The Meta-stable zone and (c) The Labile zone.
(1) Unsaturated/Not saturated : Unsaturated solution is when it can still dissolve more solute. Any solution that hasn’t yet reached its limit.
(2) Meta-stable Zone : where spontaneous formation of crystalline nuclei in the solution is impossible, but in this region, it is possible to grow a single crystal from a seed.
(3) Labile Zone : is where there is spontaneous nucleation or crystallization when the solution reaches its stage of saturation.
(4) It is understood that saturation of the solution has been achieved when any additional substance that is added results in a solid precipitate.