I recommend soaking the tapioca pearls in 2 cups of water the night before as it reduces some of the excess starch and means less cooking time.
In a 1-1/2 quart saucepan, combine the tapioca pearls, the milk, and salt. Stir frequently on medium-high heat until the mixture comes to a boil. Reduce heat to minimum and simmer 5 minutes. Add the sugar in gradually, stirring constantly.
In a separate bowl, beat the 2 eggs. A little at a time, add some of the tapioca mixture to the eggs and continue stirring. This is tempering the eggs and will bring them up to temperature gently, preventing the eggs from scrambling.
Add the tempered egg mixture to the tapioca. Gently bring the mixture back up to near-boiling. Reduce heat to minimum and simmer, stirring constantly, until desired consistency is reached. Pearls should be translucent and gelatinous.
Allow tapioca to cool 15 minutes before adding the vanilla. Serve warm or chill until serving time.