[lukxiaofung]

why i still see some crystal of NaCl(salt) in water after i dissolve the salt in water?

[AWK]

NaCl dissolves in water rather slowly up to 36 g /100 g of H2O at RT  (~26 % w/w)
and 39 g/100 g H2O at 100 C (~28 % w/w)

[Demotivator]

How do you know you have pure salt? You could have silica filler or impurities unless it's reagent grade.

[lukxiaofung]

Actually I am going to get a bigger crystal of NaCl by crystallization,but it is fail. Any things that I did wrong?
First,I dissolved some salt in the water(~RT) until the solution saturated.
Then,I left it somewhere.
Finally,the water evaporated and the salt appeared again.