This may often arise from the things that we experience every day. There are moments when you would be paying attention more to your environment. You may notice small things that you never noticed before. This can make you create research questions in your head. When you get some ideas, you are recommended to write them down.
Who knows, you may be the first person who has thought of that research question and it deserves to be researched and answered in the future. The more that you write down research questions, the more knowledgeable you can become when you find the answers to them.