Plum Wine

Step 6 "Ferment until dry"

You should notice a couple of things:

Bubbles rise in the brew.
Gas escapes through the fermentation lock, making a 'glop' noise.
When this slows down after a few weeks add the rest of the sugar, as in step 5, and let it go again.

When fermentation is complete:
No bubbles rise in the brew.
No gas escapes through the fermentation lock.
Yeast starts to settle to the bottom.

The pictures used here are of a batch which was made with white grape juice concentrate, the previous images are of a batch made with red