For the next few centuries, candy innovation moved to the Arab world. The most important discovery of this period was hard candy (called “boiled sweets” in England). See hard candy. This process requires syrup to be boiled to the hard-crack stage, when it is only about 1 percent water. See stages of sugar syrup. If this syrup is cooled quickly, it has no crystalline structure and is technically just a super-cooled liquid, like glass. In fact, molten hard-crack syrup can be worked using the same tools and techniques that a glassblower utilizes.