I don't think they're very popular today, but when I was a kid, I had a Radio Shack Electronic Project Kit [1], and I learned so much from it. Looks like you can still buy them though. [2]

[1] https://www.flickr.com/photos/samwibatt/773052449

[2] https://www.amazon.com/Maxitronix-200-in-One-Electronic-Proj...