White spots are scales. It has something to do with water quality. After the water is boiled, the crystals formed by impurities and minerals in the water will adhere to the bottom of the pot, which may be minerals such as magnesium carbonate and calcium carbonate, so scale will be formed, especially if the tap water that has not passed through is directly boiled in a stainless steel pot, which will form more scale after a long time.

Proportion:

Scale is due to the long-term use of some containers that are often in direct contact with water, and a thick layer of impurities will grow on the inner wall. The general reason for the formation of scale is that calcium sulfate (CaSO4) slightly soluble in water is precipitated by evaporation of water after repeated combustion in the container, and the original dissolved calcium bicarbonate (Ca(HCO3)2) and magnesium bicarbonate (Mg(HCO3)2) are decomposed in boiling water, thus forming scale.