Popping sound coming from strut area

I have an 01 prius and have noticed a popping noise coming from the passenger side in the strut area. I thought it might be the strut, but is not affecting my driving. I just got new tires and had them check the struts. They said they are fine, one was leaking a little, but not much. What else could be making this noise?

1. The strut. Lack of a fluid leak does not mean that the strut is good. Unfortunately there's no accurate way to assess the strut is good without removing the coil spring and manually compressing the strut, comparing to a new part. The difference in road feel between good vs. bad struts is not that great.
2. Worn front stabilizer bar bushings.
3. Loose suspension hardware.
4. A loose object, maybe in the glove box or cowl area?

The nut holding the top of the strut into the mount might be loose.

Does it make the noise when it goes over a bump or crack?
If so, it could be the strut mount.