The blooms are a major constructive consequences of errors committed when using water for mixing mortar or in contact with dirty items that might contaminate the water.
Blooms are stains in the surface of the tile due to salts and carbonates. This situation is perfectly avoidable by taking humidity basic preventive measures.
The humidity rises by capillary action and exudes from the sunniest or most ventilated areas. Water, which is mixed with other substances in solution, evaporates but not so the substances remaining in the surface of the tiles showing the problem.