How to get double loot and XP from a Pokestop?

While spinning PokeStops, I was able to get double loot (7-8 items) and double XP (100 XP) twice. However, I do not understand whether I did something special for this and I cannot find any information on this matter.

Does anyone know how to get these double loot and XP from spinning a PokeStop?

Update: faced this again. Images are below. This was the first pokestop for a long time.

Solution 1:

I have found that every 10th unique Pokéstop spun will give you 6+ items, 100 XP and an egg (if space permits), but you have to follow a specific pattern. Basically, if you continue to spin unique Pokéstops, every 10th stop will give you the bonus. Someone test this out for me.

Solution 2:

Loot is just random. sometimes i get 3 items, other 7. XP in my personal experience is related to the number of items you get. 100xp with more than 5

source: hours and hours of playing

Solution 3:

If you get multiple xp gains in a short time, the game will only display the total once. It may be that.

Look in your history journal if you want to double check.

Solution 4:

There are two possible causes for this "double loot and XP" phenomenon:

• Sheer Luck
  Pokestops have a chance to randomly spit out double loot. Perhaps you were just lucky and managed to hit the right random number.
• Unique Spins
  If you're in a new area and spin 10 (untouched by you) Pokestops within 30 minutes, the 10th Stop will automatically grant you 6 or more items, an egg (if you have inventory room), and double EXP from a single swipe.