Lilian,
We tend to use "some" instead of "any" when we expect a positive answer to the questions we are asking or when we are offering or requesting something that is already there.
Would you like some bread? This is an offer of the bread you have.
Could I have some water? You know the water is there.
Could you get me some rice when you go shopping? You know there is rice at the grocery.
For instance, you go to a grocery store in Antarctica because you want apples and you ask “Do you have any apples?” because you want of know if the merchant sells apples.
You have been looking for apples all day and can’t find them. A friend tells you about a store that has lots of apples. You go to the store expecting to find apples there. You don’t see them so you ask the merchant “Do you still have some apples? A friend of mine told me that you sell apples here.”