Much later, I decided to dye enough wool to actually make something, since I liked the intense color.
This is what I got. I suspect the difference in water might be the cause. Time for more experiments, this time using distilled water. The two samples are slightly different; the one on the bottom was simmered for much longer.
I dissolved 2 packets of sugar-free koolaid in a bowl of water. Then I added about an ounce of wool, and put the bowl in the microwave until it was hot but not boiling. (Be careful not to change the temperature of wool abruptly or boil it, as it will tend to felt.) I then let the whole mess cool, removed the wool and rinsed it thoroughly. I was expecting garish colors, but the more muted tones I actually got are very pretty.
The flavors from top to bottom are: limeade, lemonade, orange, "blue" (whatever flavor that actually is), grape and cherry. After dyeing, I spun these samples using my favorite Turkish (x-shaped) drop spindle. The yarn now smells nice too!