What is the scientific principle of "looking at the sky with salt"?

An elder led the villagers to travel day and night to transport salt to a certain place and exchange it for barley for the winter. One night, they slept in the wilderness under a bright starry sky. The elders still use the method passed down by their ancestors for generations, taking out three salt blocks and throwing them into the fire to divine changes in the weather in the mountains. Everyone is waiting for the "weather forecast" from the elders. If you hear the "crackling" sound of salt blocks in the fire, it is a sign of good weather. If there is no response, it means that the weather is about to get bad and wind and rain are coming at any time. The elder looked serious, because the salt block made no sound in the fire. He thought it was unlucky and advocated leaving as soon as dawn. But another young man in the tribe believed that "peeping into the sky with salt" was too superstitious and opposed the hasty departure. In the afternoon of the next day, the weather suddenly changed and it was windy and rainy. Only then did the young man who insisted on leaving late believed the experience of the elders. In fact, there is a scientific reason for the elders to do this. Whether the salt block makes a sound in the fire is related to the humidity in the air. When wind and rain come, the humidity is high, and the salt block becomes damp and naturally becomes silent when put into the fire. Otherwise, the salt block will make a noise. Young people look down on the experiences of old people and one-sidedly regard them as outdated and useless. In fact, some people's experience is like sea salt. No matter how old it is, it is still a kind of crystallization and has the memory of the sea. If people lack it, they will not be able to survive. This means that without the experience of our predecessors, we would still only live in a primitive society and live an animal-like life. However, living a life based on experience, putting on an air of experience at all times, and liking to drive an old car and follow the same old road will only lead to being eliminated by society.