Some metal hydroxides forms precipitates, and some are solutions. Some hydroxide precipitates are dissolved when we add more water to the compound. Some hydroxides such as 3d metal's show different colours. Some metal hydroxides are amphoteric compounds and they react with both acids and alkalis.
These hydroxide are dissolved when excess water is added to the precipitate. When metal hydroxide concentration is increased, it is precipitated.
3d metal hydroxides are insoluble in water. d block metals OH- show colours. Colours of precipitates are noted with respective compound. Colours of these 3d metal hydroxides can be used to identify the 3d metal.
These 3d metal hydroxides are precipitates and they show different colours.
Some metal hydroxides are amphoteric compounds. These hydroxides are not dissloved in water. But adding excess NaOH(aq) to these precipitates, they dissolve in the water. Also amphoteric hydroxides dissolve in dilute acids such as HCl, H2SO4. Colours of amphoteric metal hydroxides are noted with the compound.
This is the summary of solubility of all metal hydroxides.