So, here is something that most of us understand would work but is still kinda fun to try it out. Here is what you do:
- Pick a high performance aircraft, such as the TBM or any of the airliners. This could be fine in a C152 but is more dramatic in the above mentioned.
- Pick a West facing runway (240-300) at an airport that has an unobstructed view out over the ocean from the runway (large enough lake would also work)
- Choose clear skies so the clouds don’t get in the way.
- Set the time a few minutes before sunset. You can find the sunset by searching online (Bing) for the sunset time for the area your airport is at.
- Start the flight and now watch the sunset by waiting for the last sliver of sun to drop below the horizon.
- After the first sunset, add full power and climb quickly to 10,000 feet and, sure enough, the entire sun will return, like it never left. Set your autopilot to 10,000 with the heading so the sun will be in front of you.
Sure enough, the sun will set on you again, for your second sunset.
At this point you can move on, or you could quick climb to 20,000 and get your third sunset.
A great airport to do this at is to depart runway 26L at PHNL. A perfect destination would be PHLI as it will give you plenty of time to see two sunsets. I did this earlier today in a 787 and it worked perfect, proving a globe earth in MSFS. 
This in reverse would also work for multiple sunrises. Let me know how many sunsets or sunrises you can get in one climb out or descent.