Sodium chloride (NaCl) and silver nitrate (AgNO3) are both solids that are highly soluble in water. They give a double displacement reaction where the ions switch places and give sodium nitrate (NaNO3) and silver chloride (AgCl) as the products. Silver nitrate is also very soluble in water, but silver chloride is highly insoluble in water and will precipitate out of solution as a white solid. The balanced chemical equation is written below.
NaCl (aq) + AgNO3 (aq) --> AgCl (s) + NaNO3 (aq)
So two colorless solutions will give a milky white suspension when mixed.