If you do not pay the debts that you have incurred overseas, you should not expect to have a clean slate in the particular country that you have gotten these. Apparently, the creditors would surely make the necessary steps to recover the amount that they have loaned to you through legal means. If it seems difficult for them to make sure pursue this in your current country, they would at least make sure that you would not be able to return to theirs without having to repay the debts that you have incurred.
Another step that they may take is to hire debt collection agencies in your current country. Such firms may also employ legal maneuvers in order to compel you to pay up for the loans that you have acquired abroad. The presence of debt collection agencies in the country that you are currently in are actually the most potent mechanism that would serve the interests of the creditors abroad. Once these are hired by your creditor, they would certainly do everything legally allowed to make sure that you pay up. This is especially true if they actually paid the debt themselves because they believe that they could recover it from you.
You can never live an absolutely trouble-free life if you have debts that are unpaid and overdue, wherever in the world this may be. One way or another, these would certainly hassle you. If not in the immediate future, it could annoy you maybe in years after. This is the reason why you should avoid having unpaid debts. If there are circumstances when you have to leave a country for another without having to deal with your debt repayments first, you could always do this even when you are abroad. Technology has made this possible.
Obviously, debts incurred overseas are not exactly done deals. Of course, the pressure may no longer be too strong as you are far away from the reach of the mailed bills. But then, this does not really absolve you from your debts. Wherever you would be, you would still be obligated to repay it. The best that you could do is to repay the debt but according to your terms of payment. If the creditor sees that you are repaying despite your distance, they would not mind the delays.