When you stir the water,the salt disappears--it becomes part of the water.When you heat the water,you can see a white cloud which is made up of small drops of water--it is not steam,which is invisible because it is a colorless gas.Finally,when water starts to dry up,the salt turns into crystals.
这里的crystal是晶体的意思,晶体是固态物质的一类,是内部质点在三维空间成周期性重复排列的固体,具有长程有序,并成周期性重复排列,有规则的几何形状,各向异性.salt是盐,是一类金属离子或铵根离子（NH4+）与酸根离子或非金属离子结合的无机或有机化合物.无机盐包括氯化钠,硝酸钙,硫酸亚铁等,有机盐包括苯酚钠、乙酸钠、乙酸铵、盐酸苯胺等,在这里特指食盐（氯化钠）.希望我能帮助你解疑释惑.