To erupt
To burst into bloom; to flower.
Of the surface of a material: to become covered with a powdery salt (as described in sense 3.2).
Of a salt: to seep through some material (bricks, concrete, earth, rock, etc.) in a dissolved state, and then crystallize on a surface in a powdery form.
Of a substance: to change from being crystalline to powdery by losing water of crystallization.
Of something hidden: to come forth, to emerge; also, to reach full glory or power.