Bonds, binding employees to an employer for a period of time, are not legal in India. By the parlance of justice, no company can make employees sign bonds of employment. The legal framework has endorsed that the relationship between an employee and employer is no longer a slave-master relationship. Those days are gone.
So most of the companies do not call them bonds. Agreements, on the other hand, are legal and binding on two or more parties who sign it. Because of this reason, most of the companies make the employees sign an agreement to serve them for a period of time. And to reinforce the legality of the document, the agreement will normally say that the employee will be imparted some form of training during the tenure of the employment, towards which the company will be spending some amount (the amount will normally be specified), and because of this, the employee agrees to serve the company for a specified period of time post this training etc.
Companies who have fought legal cases know this but get bond signed to retain employees by indirect threatening. Most bonds are illegal. Even by case laws, Govt. and PSUs have also lost cases on this subject.
If it is a routine service bond, you need'nt worry, nothing will happen. But if they have spent money/special efforts on you in reference to any specific clause in the bond, they have the right to recover the money from you, legally.
However as you mentioned that previous employee has resigned in similar manner, so would suggest you to convince your employer regarding the same. Further get the bond examined by a lawyer and if they have not spent money on you and that you have sufficient evidence which can proof that they do not have the right to recover the money from you, legally then you can send them a legal notice demanding them to relieve you and further in the said legal notice you must specify those two cases and latter file suit.