if I were to dissolve baking soda in water and then evaporate the water would the baking soda still be there or would the entire solution evaporate away?
Sounds like a science project!
Sodium bicarbonate isn’t volatile at room temperature and pressure, so I don’t see where it would go.
It’s all still there.
If you’re not part of the solution, you’re part of the precipitate!
It would still be there, but it wouldn’t form the same homogeneous-sized powder you put in. The precipitate would be likely to form rings or plaques. It would look similar (and in fact have a similar composition) as the “calcium” deposits left behind by hard water (which aren’t calcium, they’re mainly calcium carbonate and bicarbonate).
Also, the powder is bicarbonate and the precipitate would likely include some carbonate.
Thanks for the replies, no particular reason for asking I have just thought about it a number of times and thought I would ask.
Alternately, you can heat up sodium bicarbonate and convert it to sodium carbonate, a different powdery white base, and release some carbon dioxide and water in the process. Sodium carbonate is also known as “washing soda”, and is occasionally used in some recipes.
I vaugely remember this experiment in high school chemistry. I think we used salt and water. Heated it, captured the steam, and left the salt in the beaker.
I recall my 15 year old self being very impressed. Chemistry experiments were fun. I didn’t enjoy the detailed math to balance a chemical equation. 
But it was satisfying to see what we worked out with a pencil & paper actually work in the lab. I took two semesters of Chemistry in college and briefly considered it as a major. Conversations with other students made me realize I probably wouldn’t make it through the advanced classes.
As Nava pointed out, the salt or baking soda left behind isn’t as fluffy as the processed stuff we buy. But it’s still easily identifiable in the beaker.
I think I remember a cookie recipe that called for bi carbonate soda,
Depending on the cookbook, it could be “bicarbonate of soda” or “baking soda.” Same thing. Plenty of baked goods call for it, if there is an acidic component in the recipe to react with it (often stuff like chocolate, buttermilk, brown sugar, cream of tartar, etc.). Some use both baking soda and baking powder (baking powder has both a dry acid and base, so when exposed to moisture, it reacts to form carbon dioxide.) Many just use one or the other.
We tend to use ‘baking powder’ these days as it is a more effective raising agent.
“Baking powder is a raising agent that is commonly used in cake-making. It is made from an alkali, bicarbonate of soda, and an acid, cream of tartar, plus a filler like cornflour or rice flour which absorbs moisture.
The powder is activated when liquid is added, producing carbon dioxide and forming bubbles that cause the mixture to expand. For this reason, it is important to get your cake mixture into the oven quickly once the ‘wet’ ingredients have been added to the ‘dry’ ingredients.”
That is one possible formulation of baking powder, but it certainly isn’t the most common one at least here in the US. I’m not sure any of the commercial baking powders are those two. The acid is usually something else. For example, in Clabber Girl brand, it’s sodium aluminum sulfate and monocalcium phosphate. Calumet brand, the same. Rumford just has the monocalcium phosphate for the acid.
Many of these have two acids because they’re “double acting” baking powders. They react upon mixture, and then again when exposed to heat. That’s what the sodium aluminum sulfate (or phosphate) is for. It reacts with the bicarbonate at baking temps. However, monocalcium phosphate can also react at both the addition of liquid, and then again at baking temps, so you’ll find “aluminum free” double-acting baking powders that only use monocalcium phosphate.