Sugar solutions are boiled to form a syrup that will vary in its concentration or density and thus can be used to make a variety of desserts. It may be added to other ingredients to form buttercreams, Italian meringue or marzipan. It may also be used by itself as a dessert syrup or a poaching syrup or even be caramelized to decorate a cake.
The longer a sugar syrup is boiled, the more concentrated it becomes and the harder it sets when it cools, so the stage to which you allow your syrup to cook will precisely determine the final texture of your product. Since evaporation of the water is what determines the final concentration, the initial proportion of water to sugar is not the most crucial element. If you begin with a large amount of water, you simply must cook the syrup longer before it reaches high-sugar density. There should always be enough water to dissolve the sugar, however, and best results are obtained if the syrup requires only brief boiling before it reaches the desired consistency. Since the majority of the syrups we use for our confections are supersaturated solutions, we must always be concerned with the degree of crystallization.