Why does your mother boil milk twice on a hot summer day?

My mother boils milk twice on a hot summer day to ensure that it is thoroughly pasteurized, which helps eliminate any harmful bacteria that might thrive in warmer temperatures. The second boiling also improves its shelf life, making it less prone to spoilage in the heat. Additionally, it helps to enhance the flavor and texture, ensuring a creamier consistency for dishes like yogurt or puddings. Overall, it's a precautionary measure to maintain quality and safety.