This nugget derives entirely from a post by 1926 on the Mancala Discussion Board, so he should get the credit for it and not me...
If there are three seeds left it is (may) still be possible to capture two seeds.
If all of the seeds are on your side of the board you need to end up with one seed in Pot (position) 6 and two seeds in Pot 5.
Next you distribute Pot 5, leaving two seeds in your Pot 6 and one in your opponent's Pot 1.
Your opponent is now forced to distribute (his) Pot 1.
Your only move now is to distribute Pot 6, which gathers two seeds for you.

When I saw 1926's post on the Mancala DB I didn't think it was possible to gather any more seeds when there were only three left.
I looked again and discovered that my assumption was wrong.
Ironically enough, this ending is very similar to the 3:1 ending which I have written about in another nugget.