The sugar is boiled until it is frosted like a white cotton ointment and does not stick to the hands, so as to ensure that the sugar is fully dissolved and form a uniform syrup. In the process of boiling sugar, slow cooking should be adopted to avoid too little water or too low temperature, otherwise the sugar will not completely dissolve. When the bubbles of boiling sugar become thinner, it means that the syrup has reached an appropriate concentration and can be turned into sand. The syrup treated in this way is easier to handle and will not have the texture of sand.