Some of the adhesive might leak through, but if the mix is correct, it shouldn't.
Get a scale and weight water and adhesive powder as per manufacturer's instructions.
I prefer to rely on a scale rather than my eyes and I get a consistent mix every time.
Little tip: unless you're a fast tiler, get the slow curing adhesive (3hours with 60/90 minutes pot time) and a clean tub with lid to keep the adhesive in between tiles.
Empty 15 litre paint pots are perfect.