Why doesn't my caramel sauce thicken? The actual measurement of the caramel sauce is 50g sugar : 20g water. I divided it to 17g of sugar to 7g of water, but after following the necessary procedures the mixture doesn't boil, and nor does it thicken. Why is it so?
I boiled for almost 30 minutes in medium heat though.
Also, caramel sauce is supposed to be thickened by concentration right?

(This is the link to the procedure that I had used to make caramel sauce.)
Sugar "boils" at a temperature much higher than water. The water is there just to get things started, so you don't burn the non-melted sugar directly in contact with the pan at. Within a few minute the water will have evaporated, and all you have left is liquid sugar

Use a candy thermometer and slowly raise the temperature until you get the sugar colour and flavour you want

When it cools it will thicken, or become solid, depending on how high you heated it. It is not just a time thing, it is the maximum temperature your reached

Caramelisation with happen around 170°C (340°F) depending on what type of sugar you use. Caramel sauce usually requires the addition of a fat like cream