Liquids in bottles over 3 oz. aren't a problem if you'll be checking your luggage. You can put the big bottles of shampoo, condition, hair gel, etc. in the big suitcase that gets checked at the counter.
But if you like to try and travel with only a carry-on as we do, the TSA 3-1-1 rule can be a challenge. Depending upon the trip (domestic or international) and how long we will be gone, there is a large variety of items I try and fit into our 1-quart zip bags. I usually bring at least a travel size toothpaste and shampoo to get us started. When we get to our destination, I'll sometimes go into a local supermarket or pharmacy (yes, even overseas) and buy what we need in its larger container.
But there are a bunch of creams and ointments I like to take along, "in case of emergency", and I really don't want to buy large sizes at our destination. Some items I might even have trouble finding, such as insect repellent. And I still laugh when I think about trying to locate sunblock in a South American supermarket.
Therefore, when I read about items that I can purchase as a solid, I sit up and take notice. Cutter Outdoorsman insect repellent is available as a solid that is 30% DEET. It can be found in drug stores and in outdoor gear stores. Sunblock is also available as a solid. Neutrogena has an Oil-Free Sunblock Stick. Seen at CVS, if it is not available in your local store, it can be purchased online.