As Theresa May won the Conservative party no-confidence vote, Brexit is very likely to happen. I will explain how Brexit might provoke another financial crisis.
If Brexit happens, Britain will lose many investors as a lot of those people are from abroad and they will prefer to do their businesses in more stable countries. Because investors are people who put money into financial schemes, property ect. with the expectation of achieving profit, those who are from abroad (or even not) will want to invest in more secure coutries. Therefore Britain might not have enough investors, and eventually run out of money.
No importing goods:
If Britain stops importing goods from other EU countries, there would not be much. Many fruits and vegetables come from different countries which are all in the EU (Poland, Spain, Portugal ect) landing into British supermarkets' shelves. This means, if Britain leaves the EU, we cannot import the goods as we will also leave the Single Market.
If Britain leaves the EU, it will be much more difficult to travel to different countries for vacation, business ect. It is estimated that the prices of travel will increase, and as people who live in Britain travel often, more money will be spent, which might cause a financial crisis. This point can refer to both of my previous points, as some who choose to stay in Britian might have to travel for investment requires, and some will have to try to import goods.
I think all of these reasons may lead to a financial crisis because of the money that has to be spent during Brexit.