Maktet Change Volatility without Reason

Hello,
Today(Friday) i saw the prices for the GBP moves bearish for 80 pips in 15 min chart.

I am not experienced trader but using my breakout technique and trading in a big news sometimes,
i think i had understand how market moves and why.

Today trading only in London session i saw the price of GBP falls much in the opposite direction of the trend.I saw those moves only if a high new released.But this time there wasn’t any new ,which it will effect much the price.
Why this happend?

Market never warns traders about its movement . It can change any time smooth to volatile or volatile to slow position. How and when it will do this no one knows. This is called uncertainty which is special quality of forex trading. A trader should remain prepare for any market condition.