During renovation I have used all kinds of dry compounds, be it mortar, conrete mix, tile glue, grout, plastering mud, ... On every one of them the instructions say to add the dry mix to water and mix thoroughly.
Is there any reason behind this order?
Yes, there is a very good reason. If you add water to dry mix in the bottom of the container, you get a nearly impossible to incorporate glob of the dry mix at the bottom.
On the other hand, if you add it from the top, it's much easier to get it all incorporated.
This works with everything from pancake mix to drywall compound.
Try it each way and you'll see for yourself.
From Chemistry: "Do like you oughtta: add acid to water" . Besides the "glop" problem mentioned in the answer, there is almost always released heat when dissolving something in water. If you start with lots of reagent and little water, the water may boil, leading to rather undesirable dispersal of hot reagent.
If you pour liquid onto a powder, the powder gets disturbed and swirls up into the air. It can hit you in the face.
The liquid beads up due to surface tension and runs down the hillock of powder without wetting it out. You get lumps forming, some of which which are dry in the center and require mechanical action to break up.
