I have about 30 types of glue and sealant in my garage. I've had to use these tubes of stuff for anything from creating a surf housing out of plexiglas, to fixing a hole in my boat or drysuit, to the usual home maintenance stuff.
Recently, I had a small job sealing a hole in my house. I found these three tubes of sealant that I had used over the past 10 years. I had used all these tubes of sealant about 10 years ago, then sealed them up and never used them again.
Of the three tubes, only BoatLife Life Seal was useable. This is great stuff! It had not hardened at all around the cap, so I could use it immediately. It still worked just fine.
The other two products, GE Silicone II and DAP Auto/Marine Sealant, had frozen up completely. I cut into the bottom of the tubes (you can see this in the photo), and they were solid.